Magnetic chuck



Sept: 9 1924.

s. KARASICK MAGNETIC CHUCK Filed April 9-. 1919 2 spun-sheet 1 Sept. 9',1924. I

s". KARASICK MAGNETIC CHUCK Filed April 9.. 1919 2 Sheets-Shut 2Patented Sept. 9, 1924.

UNITED STATES SAMUEL KARASICK, OF NEW YORK, N. Y.-

monnrro cnuox;

Application filed April 9,

i To all whom it may concern:

Be it known that I, SAMUEL KARASICK,

a citizen of the United States, residing at New York, State of New York,have invented a'new and useful Magnetic Chuck, of which the following isa specification. This invention relates to electromagnetic lifting andholding devices,.and more particularly to that class of devices whichare known in the art as'magnetic chucks.

In devices of this character it has formerly been necessary to have asource of direct current to energize the same and in case onlyalternating current was available it was necessary to obtain a directcurrent generator in order to provide the necessary direct current.

The present invention has for its purpose the construction andarrangement of parts in a magnetic chuck, whereby the same may beenergized by either direct or alternating current and whereby the workto be held is at all times firmly attracted to the device when actuated.This important result is obtained without readjustment of parts orwithout the heating of the'device.

It is also the purpose of this invention to provide a magnetic chuckwhich is simple to assemble, inexpensive to manufacture and which isreliable in operation. Other features not specifically mentioned willappear from the description and appended i il d I F i n t e rawin' i 1represents a perspective view of a pr eferred formv of the invention. Aportion of the chuck has been broken away in this view in order topartially show the arrangement of the parts; Fig. 2 shows a modifiedform of magnetic chuck also in perspective with a portion of the devicebroken away to show the construction and arrangement of parts; Figs. 3and 4 show modifications wherein various parts of a chuck are providedwith an arrangement for rendering certain portions of the deviceelectrically sluggish 5 Fig. 5 shows a diagrammatic view of Fig. 3, andFig. 6 is a diagram showin the relation between the flux and time w enthe arrangements shown in Figs. 3, 4 and 5 are empkiyed.

eferrmg to Fig. l ofthe drawings, the.

. numeral 1 designates a-core. This core is built up of a pluralityoflaminae, each of which Is made of a stamping from sheet metal having abody portion 2' provided frame; While thus arran .magnetic material,such as bb1tt1n 1919. Serial N0. 288,747.

with a series of integral uprights or co,

elements 3 and extensions terminatin in lugs 4. In casexthe chuck isdesigned to use alternating current, the laminae are first shellacked orenameled and then riveted together in any Well-known manner to form anintegral structure. The core 1 when thus assembled is placed in asuitable mold or support and a base 5 of aluminum or other materialhaving the properties and characteristics of this metal is molded aboutthe core 1. The lugs 4 of the core are en aged by a lug 6 which is castintegral wit the base. When the base and assembled core have thus beenmade, each of the uprights or core elements is provided with a. spool 7provided with awell-known coil or helix for its energization. It will beunderstood that these coils may be connected in any well-known manner inaccordance with the character of the current to be supplied to thechuck. The chuck in this form is provided with a face plate on which thework to be held rests, and which prevents dust or moisture from enteringinto the core and coils of the device. Thisface plate is made up of aframe 8 and a series of polepieces 9-9, each polepiece being separatedfrom the others and from the frame 8, as will be further described.- Thepolepieces 9, like the core, are also constructed of a series of laminaewhich may or may not beshellacked or enameled as in the case of thecore, and

are held together by rivets 1O threaded through each of the laminae. Itwill be noted that the rivets compress the center portion of the laminaenear the end of the polepieces so that the ends present a concavesurface as shown in Fig. 1.. The lateral surface of the polepieces aswell as the opposing inner surface of the frame, are provided withnotches 11 which coo crate in the manner to be described. Iih assemblingthe face plate, the frame 8 is placed on a level surface and thepolepieces 9-9 are also placed on this surface within the frame, carebeing taken to separate them from each other and from the surrounding edsuitable nonmetal, is poured in the spaces 12 between t e poleieces andbetween 'these pieces and the iiame. This metal when hardened engagesthe notches 11 of the frame and ole pieces and also engages the concavesur aces of the ends of the polepieces and the sides lateral surfaces ofthe polepieces are beveled so that their lower faces are substantiallyequal to the surface of the polepieces with which they engage, in orderto lessen the leakage of flux between adjacent polepieces. On the sideof the chuck there is mounted a switch box 13 in which is mounted aswitch operating to make or break connection between the coils and thecable 14.

Referring to the modification of the invention shown in Fig. 2, there isprovided a cast metal base 15 provided with threaded, raised portions 16on its inner bottom surface. This form of magnetic chuck has a coreelement also made of a series of laminae riveted together of a formsubstantially the same as shown in Fig. 1, except 'that the lateralextensions andlugs l are not necessary in the present arrangement. Inthis case the core is fastened to the threaded, raised portions 16 by abrass screw 17. It will be noted that the core is also magneticallyinsulated from the base,

by brass washers 18. The uprights of the core are provided with spools19 upon which are wound the energizing coils for the various elementsof. the core. The open side of the base 15 is closed by a face plate 20.This face plate is substantially the same as the face plate of Fig. 1,except that the laminated polepieces have interlocking portions' Thepolepiece 21 is provided with laterally extending portions 23-2 3 whichengage similar lateral extensions 24-24: of the polepiece 22.Theselateral extensions 23 and 24 of the polepieces 21 and 22 are eachprovided with an aligning opening 25 through which a rivet 26 isthreaded to lock the adjacent polepieces in position; The polepiecesthus assembled are.

placed on a level surface with the surrounding frame of the face plateproperly positioned around them. Molten'non-mag netic material is thenpoured in the space between the polepieces and the frame, thisnon-magnetic material serving not only to I magnetically insulate eachof the polepieces from each other and the frame, but also "servesto'lock the polepieces in the frame andgive strength and rigidity to thewhole face plate.

When alternating current is employed to energize the chuck, the worktobe held on the chuck may not-always be firmly-held on its surface unlessit is provided with cer-' tain arrangements. In order to obviate thisdifficultyit is necessary to provide means which will maintain the fluxin certain por- I tions of the core until the fluxhas been built up inother portions during each reversal of current. Several differentmodifications of means forthis pur so are shown. Flg. 3 a note '27 iscut longitudinally into the surface of the polepieces 9 and a band ofcopper isplaced in this notch and tions of each of the polepieces, asshown in Fig. 4.

These various flux-maintaining devices shown are merely typical and mayhe replaced by any arrangement in which certain portions of the chuckare rendered electrically sluggish.

The effect of these devices is best shown by reference to Fig. 6, whichrepresents curves showing the relation between time and flux in thevarious portions of the cores of Figs. 3, 4 and 5. The flux in theportions of the core which are not provided with a copper jacket isillustrated by the curve A, whereas the flux through the'porti'ons ofthe core which are affected by the copper jacket is represented by thecurve B. It will thus be seen that some portions of the polepieces areprovided with magnetic flux, while the lines of force in the otherportions of the polepieces have died down to zero.

It will be understood that the present invention, although shown inconnection with I magnetic chucks, may be employed-in any relation whereit is desired to lift, hold or carry magnetic articles. It will also beunderstood that where the copper jacket has been mentioned, any othermetal may be the pole pieces, fixing the pole pieces with .a freesurface of each in substantially the same plane, and placing said polepieces ad- I jacent said core.

2. The method of forming electroma gnetic chucks which consists inassembling a core' of laminae, casting a base about said core, placingcoils onv said core, assembling the pole pieces, fixing the pole pieceswith a free surface of each in substantially the same plane, and placingsaidpolefpieces adjacent said core."

3. The method of making electromagnetic chucks which consists of makinga suitablecore element, casting a base about said element, placing coilson said core, assembling pole pieces of laminae, arranging the freeparallel planes,-and placing said pole pieces I adjacent said core.

4. In an electroma etic chuck, a laminated unitary core e ement having aplusurfaces of said pole pieces in substantially 15 of extensions, asecuring polepieces being in engagement with said projections butseparated from said frame by non-magnetic material.

5. In an electromagnetic chuck, a laminated core element having three ormore extensions, coils thereon, an inclosing structure formed ofnon-magnetic material cast integral with said core, pole piecesseparated from each other but held in fixed relation by non-magneticmaterial cast inte ral therewith, said pole pieces being place adjacentsaid core.

6. In an electromagnetic chuck, an element formed of laminae having aplurality element for clamping the laminae together, a base ofnonmagnetic material cast about and engaging the ends of said core,coils for said core, pole pieces extending at right angles to the planeof said laminae, said pole pieces being placed adjacent said core.

7. In an electromagnetic chuck, a core having three or more integralparallel extensions and free ends, a base of non-ma netic material andcast about'the free en 5 of said core, coils for said core, and alaminated pole piece engaging said extensions.

In witness whereof, I hereunto subscribe my name this 7 day of April, A.D. 1919.

SAMUEL KARASIGK.

